If you are running a stock engine then 9 trailing and 7 leading are okay . But heat is the enemy and so running colder plugs in trailing and leading will be better for the engine . the spark plug is just not there for spark but it takes the heat out of the combustion chamber and transfer it into the rotor housing or head.

 

thanks!! yeah its a stock 86 fc. it back fires at idle a good amount, i cant really hear it on decell. i didnt know if they are fouled, their stock plugs! i just fig its time to replace them haha

 

does anybody use the br10eg with good results these are resistors plugs i think that this can cure some problem that people have when they switch to a aftermarket efi system since they are resistors plugs you have less RFI do to bad grounding.